Sudoku Generator

This little program, which has no external dependencies, is a quite fast procedural Sudoku puzzle generator.

Usage

Usage of ./go-sudoku-gen:
  -output string
        The output path (@seed for auto naming)
  -save-img
        Whether to save the image or not
  -seed int
        The seed; defaults to current unix timestamp (default 1631573683595299425)
  -simple
        Shows a board without UTF-8 borders
  -solve string
        A puzzle to solve

How it works

Generating valid boards

The board is created and filled by randomizing the number that goes in each cell. If a point is reached where it runs out of possible placements, then it attempts to re-fill the board from scratch.

Generating a puzzle

In order to generate a valid puzzle, the algorithm randomly chooses which cells to empty. At the end, it will verify that there is only one possible solution, otherwise it will attempt to re-generate a puzzle.

Sample output

./go-sudoku-gen -seed 1034875

Seed: 1034875
╔═══╤═══╤═══╦═══╤═══╤═══╦═══╤═══╤═══╗
║ 8 │ 6 │ 1 ║ 4 │ 5 │ 7 ║ 3 │ 9 │ 2 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 2 │ 7 │ 3 ║ 1 │ 6 │ 9 ║ 4 │ 5 │ 8 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 4 │ 5 │ 9 ║ 8 │ 3 │ 2 ║ 1 │ 7 │ 6 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 3 │ 1 │ 5 ║ 2 │ 7 │ 6 ║ 9 │ 8 │ 4 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 9 │ 2 │ 8 ║ 3 │ 4 │ 5 ║ 6 │ 1 │ 7 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 7 │ 4 │ 6 ║ 9 │ 1 │ 8 ║ 2 │ 3 │ 5 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 1 │ 8 │ 2 ║ 5 │ 9 │ 4 ║ 7 │ 6 │ 3 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 6 │ 9 │ 4 ║ 7 │ 8 │ 3 ║ 5 │ 2 │ 1 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 5 │ 3 │ 7 ║ 6 │ 2 │ 1 ║ 8 │ 4 │ 9 ║
╚═══╧═══╧═══╩═══╧═══╧═══╩═══╧═══╧═══╝
╔═══╤═══╤═══╦═══╤═══╤═══╦═══╤═══╤═══╗
║   │   │ 1 ║   │   │ 7 ║ 3 │   │   ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 2 │   │ 3 ║   │   │   ║ 4 │ 5 │ 8 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 4 │   │ 9 ║   │   │ 2 ║   │   │   ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 3 │ 1 │   ║   │   │   ║ 9 │   │   ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║   │   │ 8 ║   │ 4 │   ║ 6 │   │   ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║   │   │ 6 ║   │   │   ║   │ 3 │ 5 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║   │   │   ║ 5 │   │   ║ 7 │   │ 3 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 6 │ 9 │ 4 ║   │   │   ║ 5 │   │ 1 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║   │   │ 7 ║ 6 │   │   ║ 8 │   │   ║
╚═══╧═══╧═══╩═══╧═══╧═══╩═══╧═══╧═══╝
Execution time: 342ms

Generating a printable board

You only need to supply the -save-img flag. The result looks like this:

Solving a raw puzzle

It's possible to solve a puzzle that's passed in as a string. Simply pass the string to the program with the -solve flag.

./go-sudoku-gen -solve 4.1...7....3.2...58.......6....7.3.4....5....2.5.9....9.......65...1.3....2...1.4
╔═══╤═══╤═══╦═══╤═══╤═══╦═══╤═══╤═══╗
║ 4 │   │ 1 ║   │   │ 3 ║ 8 │   │   ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║   │   │   ║   │ 2 │   ║   │   │   ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 7 │   │   ║   │   │ 5 ║   │   │ 6 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║   │   │   ║   │   │   ║ 2 │   │ 5 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║   │ 7 │   ║   │ 5 │   ║   │ 9 │   ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 3 │   │ 4 ║   │   │   ║   │   │   ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 9 │   │   ║ 5 │   │   ║   │   │ 2 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║   │   │   ║   │ 1 │   ║   │   │   ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║   │   │ 6 ║ 3 │   │   ║ 1 │   │ 4 ║
╚═══╧═══╧═══╩═══╧═══╧═══╩═══╧═══╧═══╝
╔═══╤═══╤═══╦═══╤═══╤═══╦═══╤═══╤═══╗
║ 4 │ 2 │ 1 ║ 9 │ 6 │ 3 ║ 8 │ 5 │ 7 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 6 │ 9 │ 5 ║ 8 │ 2 │ 7 ║ 4 │ 1 │ 3 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 7 │ 3 │ 8 ║ 1 │ 4 │ 5 ║ 9 │ 2 │ 6 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 8 │ 6 │ 9 ║ 7 │ 3 │ 1 ║ 2 │ 4 │ 5 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 1 │ 7 │ 2 ║ 4 │ 5 │ 6 ║ 3 │ 9 │ 8 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 3 │ 5 │ 4 ║ 2 │ 8 │ 9 ║ 7 │ 6 │ 1 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 9 │ 1 │ 3 ║ 5 │ 7 │ 4 ║ 6 │ 8 │ 2 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 2 │ 4 │ 7 ║ 6 │ 1 │ 8 ║ 5 │ 3 │ 9 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 5 │ 8 │ 6 ║ 3 │ 9 │ 2 ║ 1 │ 7 │ 4 ║
╚═══╧═══╧═══╩═══╧═══╧═══╩═══╧═══╧═══╝
Possible solutions: 1

License

Although the source code is licensed under GNU GPLv3, I prohibit the use of this code for the purpsoses of training any kind of AI model. This applies to any version of the source code and/or commit, historic, current, and/or new.